The title salt, C20H42N4S22+·2ClO4-, was obtained from the reaction of bis(diethylamino)carbeniumdithiocarboxylate, (Et2N)2C2S2, with Fe(ClO4)2·6H2O in CH2Cl2. The title compound, in which one of the S atoms of (Et2N)2C2S2 is bound to a 1,1-bis(diethylamino)ethane moiety, has two carbenium C atoms, and the charge compensation is provided by two perchlorate anions. The N2C-CS2 bond length is 1.512 (4) Å, corresponding to a C-C single bond, and the dihedral angle between N2C- and -CS2 planes [72.0 (2)°] is smaller than that of (Et2N)2C2S2 [82.0 (1)°]. The crystal structure features C-HS hydrogen bonds.

In the process of a preparation of iron(II) complex with
bis(N,N-diethylamino)carbeniumdithiocarboxylate
[(Et2N)2C2S2] (II) (Fig 1), we obtained the unexpectedly
bis(diethylamino)-methylium bis(diethylamino)-2-ethyliumcarbodithioate
perchlorate [(C10H20N2S2)(C10H20N2)](ClO4)2 (I) and
report here its molecular structure. We suppose that I was formed
through an oxidation of II, which has taken place under gentle
conditions for several months in solution. The molecular structure of I
is shown in Fig. 2. The C11–S1 bond length is 1.794 (3) Å, which
corresponds to the C–S single bond [1.79 (1)–1.82 (1)Å; Miller et
al., 2000; 1.78 (4)Å; Nakayama et al., 1997]. The
N–C(CS2)
bond lengths in the range of 1.316 (4)–1.333 (4) Å are slightly shorter than
the normal C(sp3)–N(sp3) bond length (1.36Å; Allen
et al., 1987) suggesting that the C2 and C12 atoms are
carbenium
carbons. The bond lengths of C1–S2 [1.615 (3) Å] and C1–S1 [1.729 (3) Å]
are close to those of the CS terminal and the –C–S– bridging bonds of
methylated species of I, respectively [1.608 (14)Å and 1.714 (13)Å,
respectively; Nakayama et al., 1997], indicating localization
of
electron on S–C–S moiety. The C1–C2 bond length [1.512 (4) Å] and
dihedral angle between N2C– and –CS2 planes [71.99 (22)°] are slightly
longer and smaller, respectively, than those of II
[1.477Å–1.506 (2)Å and 82.0 (1)°, respectively; Nagasawa et al.,
1995], and these change mean that decrease of interaction between the
unfilled
p orbital of carbenium carbon (C2) and electrons on S–C–S moiety.
The C11–C12 bond length 1.523 (4)Å is slightly longer than that of C1–C2.
The S1–C1–S2, N1–C2–N2, and N3–C12–N4 bond angles are similar
values for those of II [S–C–S: 129.4 (8)° and N–C–N: 122 (1)°;
Nagasawa et al., 1995]. Two ClO4- per one I exist as
counter
ions in the crystal. The crystal structure consists of a chain structure
through intermolecular weak C—H···S hydrogen bonding
[H14B···S1': 2.9138 Å, C14–H14B···S1': 176.69°]
(Fig. 3 and Hydrogen-bond
geometry).